Method and system for magnification correction from multiple focus planes

• US 9,338,363 B1
• Filed: 11/06/2014
• Issued: 05/10/2016
• Est. Priority Date: 11/06/2014
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (GE Vernova, Inc.)
• Original Assignee: General Electric Company
• Inventors: Harding, Kevin George, Batzinger, Thomas James
• Primary Examiner(s): Jerabek, Kelly L
• Application Number:
  US14/534,837
• Publication Number:
  US 20160134816A1
• Time in Patent Office: 551 Days
• Field of Search: 348335-344, 348360-361, 348/218.1, 348/239, 348/240.1, 382115-116, 382/124, 382/126, 737/60, 737/88, 737/99, 738/00
• US Class Current: 1/1
• CPC Class Codes: G02B 13/0015 characterised by the lens design
• CPC Class Codes: G02B 27/0075 with means for altering, e.g. increasing, the depth of field or depth of focus
• CPC Class Codes: G02B 7/38 measured at different points on the optical axis , e.g. focussing on two or more planes and comparing image data
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/571 from focus

Abstract

A method for correcting a magnification in image measurements is implemented using a computer device including one or more processors coupled to a user interface and one or more memory devices. The method includes acquiring a plurality of images of a target. Each image is acquired at a different distance from the target. The method also includes determining a distance between a lens used in acquiring the plurality of images and the target and determining a magnification of each acquired image. The method further includes determining a magnification correction with respect to a reference, determining a change in a size of the target, and outputting the determined change in a size of the target.

Claims

1. An inspection imaging system configured to use magnification correction from multiple focus planes, said system comprising:

an imager comprising an image acquisition device and a lens in optical communication with said image acquisition device;

a controller comprising;

a user interface;

one or more memory devices; and

one or more processors communicatively coupled to said user interface and said one or more memory devices, said one or more processors programmed to;

acquire a plurality of images of a target, each image of the plurality of images acquired in a different focus plane of the multiple focus planes with respect to the target using the same optical parameters of the imager for each image;

determine a distance between said lens used in acquiring the plurality of images and the target;

determine a magnification of each acquired image;

determine a magnification correction with respect to a reference target of known dimensions;

determine a change in a size of the target; and

output the determined change in the size of the target to a maintenance planning computer system communicatively coupled to the inspection imaging system.

2. The system of claim 1, further comprising an optical path changer configured to change the optical path of light between the target and said lens.

3. The system of claim 1, wherein said processor is further programmed to receive point spread function information for said lens for determining the distance between said lens and the target.

4. The system of claim 1, wherein said processor is further programmed to determine a magnification of each acquired image using focal length information of said lens.

5. The system of claim 1, wherein said processor is further programmed to determine the distance between said lens and the target using a focus clarity of the image.

6. The system of claim 1, wherein said processor is further programmed to determine the distance between said lens and the target using at least one of a depth from focus function and a depth from defocus function.

7. A computer-implemented method for correcting a magnification in image measurements, said method implemented using a computer device including one or more processors coupled to a user interface and one or more memory devices, said method comprising:

acquiring a plurality of images of a target, each image of the plurality of images acquired at a different distance from the target;

determining a distance between a lens used in acquiring the plurality of images and the target;

determining a magnification of each acquired image;

determining a magnification correction with respect to a reference;

determining a change in a size of the target; and

outputting the determined change in a size of the target to a maintenance planning computer system.

8. The method of claim 7, wherein determining a distance between the lens used in acquiring the plurality of images and the target comprises receiving point spread function information for the lens.

9. The method of claim 7, wherein determining a magnification of each acquired image comprises determining a magnification of each acquired image using focal length information of the lens.

10. The method of claim 7, wherein acquiring the plurality of images of the target comprises acquiring a plurality of images of a pattern coupled to a surface of a component.

11. The method of claim 7, wherein acquiring the plurality of images of the target comprises acquiring a plurality of images of a surface feature of a component.

12. The method of claim 7, wherein determining a distance between the lens used in acquiring the plurality of images and the target comprises determining the distance between the lens and the target using a focus clarity of the image.

13. The method of claim 7, wherein determining a distance between the lens used in acquiring the plurality of images and the target comprises determining the distance between the lens and the target using at least one of a depth from focus function and a depth from defocus function.

14. The method of claim 7, wherein determining a distance between the lens used in acquiring the plurality of images and the target comprises acquiring a first of the plurality of images in focus.

15. The method of claim 14, wherein determining a distance between the lens used in acquiring the plurality of images and the target comprises acquiring a remainder of the plurality of images out of focus.

16. One or more non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by at least one processor, the computer-executable instructions cause the processor to:

acquire a plurality of images of a target, each image of the plurality of images acquired at a different distance from the target;

determine a distance between a lens used in acquiring the plurality of images and the target;

determine a magnification of each acquired image;

determine a magnification correction with respect to a reference;

determine a change in a size of the target; and

output the determined change in a size of the target to a rate computer system configured to determine a rate of change of the target and to forecast a time period before the target exceeds a predetermined limit.

17. The computer-readable storage media of claim 16, wherein the computer-executable instructions further cause the at least one processor to determine the distance between the lens and the target using a focus clarity of the image.

18. The computer-readable storage media of claim 16, wherein the computer-executable instructions further cause the at least one processor to determine the distance between the lens and the target using at least one of a depth from focus function and a depth from defocus function.

19. The computer-readable storage media of claim 16, wherein the computer-executable instructions further cause the at least one processor to acquire a first of the plurality of images in focus.

20. The computer-readable storage media of claim 19, wherein the computer-executable instructions further cause the at least one processor to acquire a remainder of the plurality of images out of focus.